The present invention relates to a seat or a chair unit intended primarily for vehicles of the wheelchair type and in particular motor-driven wheelchairs.
Wheel chairs are often intended to be capable of being used for persons having different bodily constitutions, bodies of varying sizes and varying handicaps. Thus there exists a need for being able to adjust the dimensions of the seat in a simple way, included therein also the dimensions of a backrest included in the seat. Also, the slope and the position of portions such as the seat cushion, footrests and armrests need to be capable of being adjusted.
Such a wheelchair is for example disclosed in U.S. Pat. No. 3,937,490 (corresponds to SE-B 402 706) and has two side frames, the distance of which from each other can be adjusted, so that the wheelchair gets different widths. Then at the same time, the distance of the wheelchair wheels of each other is changed and also the width of the seat and of the backrest, implying that they cannot be adjusted individually. The position of the backrest in relation to the front edge of the seat can also be adjusted. The backrest and the seat are made of flexible web pieces. Similar designs are disclosed in U.S. Pat. Nos. 4,375,295, 4,457,535 and 4,500,109.
However, such designs cannot be used for seats or chair upper units which are intended for motorized wheelchairs. They require a seat or a chair unit attached to the motor-driven base and in addition, generally padded cushions in the backrest and in the seat in order to provide a suitable comfort. Further, the padded cushions should then have a rigid base or a rigid bottom plate ensuring the comfort. The width and height of such cushions and the rigid bases thereof must in a simple way be capable of being adjusted to be adapted to different users.
It is an object of the invention to provide a seat, in particular a chair unit including a seat or bottom unit, against the upper surface of which the buttocks of a person is intended so to rest, and a backrest part, which is suited for different mountings, e.g. on a motor-driven base, and is adjustable in a simple manner in a multitude of ways.
It is a further object to provide a rigidly constructed seat, the total width and depth of which can be adjusted.
These and other objects are achieved with the device as described hereinafter including that the seat part comprises a central frame attached to a fixture which is intended to be attached to a wheelchair base, which can be a motorized base for a wheelchair, and side frames arranges at each side of the central frame, which are adjustably attached to the central frame. Then, by a varying adjustment of the side frames different widths of the seat part are obtained. The side frames support advantageously thin rigid seat plates or base plates, which at least at their outermost portions located at the sides rest primarily on one of the side frames. The seat plates are slidable on top of or at the bottom of each other when changing the width of the seat part, such as when adapting the side frames in relation to the central frame. The seat plates then carry padded cushions, the sizes of which can also be varied.
Further, the seat part can be adjusted in varying angles of inclination by means of a lower frame which is rigidly attached to the fixture and placed under the central frame and is hinged thereto, for example at the rear edge thereof, and an adjustment mechanism, for example a screw cooperating with a threaded bore, connected to the lower frame and the central frame, so that the central frame is adjusted in different angles in relation to the lower frame and thereby also the slope of the seat part is varied.
Further, a front frame can be provided, which is arranged at the front side of the central frame and is adjustably attached to the central frame, and/or a rear frame, which is arranged at the rear side of the central frame and is adjustably attached to the central frame. Then, by adjusting the front or the rear frame respectively, the front edge and the rear edge respectively of the seat part can be placed in different positions in relation to the fixture and thereby in relation to the seat base. The position of the centre of gravity of a person resting in the chair can thereby be adjusted in relation to the fixture. Further, thin seat plates of the type mentioned above can be adjustably attached to the front frame and/or the rear frame in order to be secured in their positions and obtain support from these frame parts.
The backrest comprises preferably two side frame portions which are attached to the corresponding side frames of the seat part. The side frame portions are connected by intermediate frame portions or cross frame portions which are attached to the side frame portions. The intermediate frame portions have adjustable lengths, so that in adjusting the side frames of the seat the length of the intermediate frame portions can be adapted thereto, so that the width of the backrest is adjusted in accordance with the width of the seat part. The side frame portions are attached to the side frames of the seat by means of hinged connections which are adjustable as to their angles. Then, these connections comprise a suitable locking mechanism for adjusting the inclination of the backrest in relation to the seat. Such a locking mechanism can comprise a first slot in a first part, such as a plate, which is rigidly attached to the backrest, and a second slot in a second part, such as a second plate, which is rigidly attached to the seat part. The second slot is then arranged so that it with its direction, which is defined by the edges of the slot, or its longitudinal axis in the geometrical sense intersects the direction of the first slot, which is defined by the edges of the slot, or its longitudinal axis so that a hole passing through the two slots is formed. Then, a locking element such as a locking screw can pass through the hole thus formed for locking the backrest in relation to the seat part. The directions of the slots are advantageously arranged in such a way that also when the locking element is located in the hole and it is not arranged for a firm or positive locking operation still a resistance is obtained when changing the angle of the first and second parts, i.e. when changing the inclination of the backrest, owing to a large friction between the edges of the slots and the locking element. The geometrical angle of intersection between the slots or their directions and/or between their edges can for example always be less than 45xc2x0 for different possible inclinations of the backrest.
Advantageously the joints between the side frame portions of the backrest and the side frames of the seat part are attachable in different positions in the longitudinal direction of the seat, i.e. along the exterior sides or edges of the side frames of the seat. In this way the position of the backrest in a direction forwards and backwards in relation to the seat part can be adjusted for adapting to e.g. a changed position of the rear edge of the seat part.
Also the height of the backrest can be adjusted and it is accomplished by the fact that it can comprise a lower frame portion and an upper frame portion which upper frame portion is attachable to the lower frame portion in different positions in the vertical direction. In addition, the upper frame portion can also be removed so that a considerable reduction of the height of the chair upper part is obtained. This can be advantageous in transporting the chair upper part. Rigid base plates for the backrest are then suitably attached to the upper frame portion and have detachable hook means for a detachable cooperation with the lower frame portion. Such backrest plates comprise advantageously two plates, which at their outermost portions located at the sides rest primarily on one of the side frame portions of the backrest. These plates are like the base plates in the seat part interlockable and slidable on top of or at the bottom of each other when changing the width of the backrest, what can be required when changing the distance of the side frame portions of the backrest.
Further, armrests can be attached to the backrest, as by means of a hinge formed by a pivot in a hole. By means of a suitably constructed pivoting mechanism they can be detached from the backrest by a rotating movement upwards to a position substantially parallel to the backrest and thereupon a displacement horizontally. Such a mechanism can comprise a slot cooperating with some suitable projecting element, such as a pin or a plate, so that in the rotating movement the slot will be disengaged from the projecting element, whereas it is engaged therewith in the normal, approximately horizontal position of the armrest or the position of the armrest that is parallel to the seat part. The slot and the projecting element should be attached to the seat part and the backrest respectively or to the backrest and to the seat part respectively. Further, the rotating joint must allow the armrest to be moved freely in a horizontal direction, i.e. perpendicularly to the plane of the rotation, away from the backrest in the case when the slot and the projecting element are disengaged from each other.
Foot- and/or legrests can be attached to the seat part by means of a hinge and a locking mechanism applied in the hinge for adjusting the slope of the rests in relation to the seat. The locking mechanism comprises advantageously a friction joint comprising a multitude of parallel, plate-shaped elements rigidly attached to the seat part and a multitude of parallel plate-shaped elements rigidly attached to the foot- and/or legrest, so that the plate-shaped elements are arranged alternatingly with each other. Further, a through-hole passes through the plate shaped elements, through which hole a common shaft extends, so that the hinge is formed. Further, means are provided for pressing the plate-shaped elements against each other, e.g. by the shaft comprising a screw or bolt together with a cooperating threading or nut.
The cushions in the seat part and the backrest can comprise a padded part having slots, which extend at and in parallel with edges of the padded part, so that edge portions of the padded part located at the side of or outside the slots can be easily removed. In that way, the padded part is reduced and thereby the width and/or length of the cushion for adaption to an adjusted value of the width of the seat part. The cushion can also comprise a cover of a flexible thin material such as some fabric or plastics material arranged outside the padded part. The cover is advantageously provided with velcro strips (bur fasteners) and counterstrips arranged at suitable places. When such a velcro strip is brought in contact with a suitably chosen corresponding counterstrip the marginal portion of the cover is folded onto itself. Thereby the width and/or the length of the cover can be reduced in order to be adapted to a reduced size of the padded part.